Catriel Beeri Peter Buneman Database Theory - ICDT '99, 7th International Conference, Jerusalem, Israel, January 10-12, 1999, Proceedings. ICDT Lecture Notes in Computer Science 1540 Springer 1999 3-540-65452-6 https://doi.org/10.1007/3-540-49257-7 db/conf/icdt/icdt99.html